I tried it some time ago for offsetting the polygon, yet it does work only for closed polygons unfortunately - while it was not my issue... so I dropped the idea.
PS there are a lot of "not completly good" things that could be good in standard GDL extensions like the one mentioned and for example: text in/out which is bind to the once typed file name unless the dialog set to pop up. (it is impossible to for example save/load some part of data to file selected by user using the OS dialog)
Best Regards,
Piotr
